1. Field of the Invention
This invention relates to a failure-recovering sequential procedure teaching system for teaching a failure-recovering sequential procedure when a failure occurs in, for example, an automatic production equipment.
2. Description of the Related Art
When a failure occurs in a sequentially controlled automatic production equipment, usually, the equipment is stopped. However, according to the equipment, when the operation of the equipment is stopped, in order to recover the failure from abnormal to normal state, the technique of teaching a failure recovery sequence to an operator or the system for automatically executing the failure recovery sequence has hitherto been proposed in various patents and publications, e.g. in U.S. Pat. No. 5,111,383, Japanese Unexamined Patent Publication No. H. 2-96205, Japanese Unexamined Patent Publication No. H. 3-230202, H. Japanese Unexamined Patent Publication No. H. 5-134719, etc. However, in such a technique or system, since monitoring of failure, classification of failure, and instruction of recovery sequence are performed in a relevant control device, it was necessary that such functions be incorporated in the control device beforehand. As the technique of classifying failures, there has been proposed a technique of dividing the operation of an automatic equipment into operational steps, monitoring the step execution time length by a timer, and classifying the step whose operation exceeds a required time length as an abnormal step, as disclosed in Japanese Unexamined Patent Publication No. H 1-248206 and Japanese Unexamined Patent Publication No. H. 4-6962, or a technique of monitoring the pattern of input/output data in each step while comparing this with normal pattern and classifying the step whose input/output data pattern is out of coincidence with normal pattern as abnormal step as disclosed in Japanese Examined Patent Publication No. H. 5-47843.
However, in such a technique, when control program is designed, it was necessary for each step to be designed so that relevant failure may be exactly grasped, or it was necessary that the control operation be of a system wherein the control operation proceeds to a next controlled step after the performance of the immediately preceding step operation control has been completed. Due to such limitation, it was difficult for such technique to be applied to an arbitrary type of equipment.